Influence of material of rotor end plate on 3-D electromagnetic field and eddy current losses in end region of hydro-generator

In hydro-generator, rotor end plate is one of the most important components, which is usually placed in the space between pole and the end of field winding, used to clamp the laminated pole and prevent the damping ring from flying off because of large centrifugal force. Generally, rotor end plate is made of 1Crl8Ni9Ti, forged steel and cast steel, which are either non-magnetic or magnetic material. Magnetic characteristic of rotor end plate affects the distribution of end leakage magnetic field, and then affects eddy current losses of end structures. Therefore, it is necessary to research the influence of magnetic characteristic of rotor end plate on the electromagnetic field and eddy current losses of end structures. In the past, scholar paid more attention on the material of stator clamping plate and clamping finger [1], however, few people studied the influence of material of rotor end plate on electromagnetic field and eddy current losses in end region of hydro-generator. In this paper, a 250MW hydro-generator is taken as an example, physical and mathematical models of 3-D nonlinear transient electromagnetic field in end region are established. When non-magnetic and magnetic materials are adopted, transient electromagnetic field and eddy current losses of stator end structures are contrastively analyzed, which will provide useful reference for the reasonable design of end structures.